Valve system for servo control of fluid flows

ABSTRACT

The present invention provides a mixing valve ( 30 ) suitable for electric motor ( 38 ) actuation, particularly stepper motor actuation. It also provides a servo mixing valve system, which includes stepper motors for actuation and optionally includes a solenoid switched outlet manifold and a combination mixing and dye. The present invention also provides an actively controlled bathroom shower mixing system including temperature formation feedback.

The present invention relates to valves for controlling the flow offluids in a fluid supply system. More particularly, it relates to valvessuitable for active servo control of fluid flows. Further, inparticular, it relates to valves for active servo control of fluid flowsin a fluid mixing unit.

BACKGROUND OF THE INVENTION

Valve systems suitable for being electrically controlled and actuatedare known for a wide variety of applications. These add the manyadvantages of control electronics and computing to their applications.

One such application, is the control of flow for shower mixers, handbasin mixers, and the like.

A commonly used conventional electrically controllable flow valveincludes a conventional faucet valve and an electric motor to actuatethe spindle of the faucet valve. The electric motor turns the spindle toaxially move the disc of the faucet valve and restrict flow emergingfrom the disc ring of the faucet valve. Typically, multiple revolutionsof the spindle are required to actuate the disk through its workingrange. Also the spindle is mounted and moved by means of a threadarrangement which introduces friction. Therefore, this type of valve isnot well suited to servo control. Also, movement of the disk to closethe valve must work against the supply pressure of the fluid.

Accordingly, it is an object of the present invention to provide a fluidcontrol valve which overcomes or obviates the disadvantages of existingsystems, or at least to provide the public with a useful choice.

It is also an object of an embodiment of the present invention toprovide a fluid control valve adapted to servo control the flow of fluidthrough the valve, or at least to provide the public with a usefulchoice.

It is an object of an embodiment of the present invention to provide aservo controlled mixing of supplied fluids in given ratios, or at leastto provide the public with a useful choice.

It is an object of an embodiment of the present invention to provide anactively controlled shower mixer which employs temperature feedback, orat least to provide the public with a useful choice.

SUMMARY OF THE INVENTION

Accordingly, in a first aspect, the invention may broadly be said toconsist in a fluid mixing valve suitable for servo control of fluidflows, comprising: a valve body having at least two fluid inlet portsand at least one fluid outlet port; a valve seat having a valve seatcontact surface and an outlet valve member having an outlet membercontact surface, the valve member being rotatable about a first axis;said valve seat having two adjacent inlet apertures there throughseparated by a dividing piece, and said valve seat having a closed areaopposite the inlet apertures, a first said inlet aperture communicatingwith a first of said two inlet ports, and a second said inlet aperturecommunicating with a second of said two inlet ports, a barrier on theinlet side of the valve seat separating the fluid flow from said atleast two inlet ports so that the two supplies of fluids do not mixuntil after they have passed through the two inlet apertures in thevalve seat; said valve member having an outlet aperture there throughand a sealing area, said outlet aperture communicating with said atleast one outlet port, the valve member contact surface and the valveseat contact surface being arranged in substantially planar sealingcontact with one another, and the valve member is capable of rotationrelative to the valve seat, wherein the outlet aperture of the valvemember is substantially sector shaped at the plane of the valve membercontact surface, with its sector apex at or close to the point ofintersection of the first axis with the valve member and with its arc ator close to the outside of the valve member, and the two adjacent inletapertures of the valve seat are each substantially sector shaped at theplane of the valve seat contact surface with each having its sector apexclose to the point of intersection of the first axis with the valveseat, and the sealing area of the valve member is greater than or equalto the combined area of the two adjacent inlet substantially sectorshaped apertures so that the sealing area of the valve member can coverand close the two adjacent inlet substantially sector shaped apertures,whereby the valve member can be rotated about the first axis between ashut off position where both of the inlet apertures are closed by thevalve member, a first inlet opened position where the first inletaperture and the outlet aperture are aligned to allow fluid to flow fromthe first inlet port through the first inlet aperture via the outletaperture to the outlet port, whilst at the same time the second inletaperture is closed by the valve member, a second inlet opened positionwhere the second inlet aperture and the outlet aperture are aligned toallow fluid to flow from the second inlet port through the second inletaperture via the outlet aperture to the outlet port, whilst at the sametime the first inlet aperture is closed by the valve member, and amixing position wherein the outlet aperture overlaps with both of theinlet apertures to allow fluids to flow from said two inlet portsthrough the two inlet apertures and through the outlet aperture, and mixdownstream of the outlet aperture so that the fluids can exit the outletport.

Preferably the valve member is a first valve disk.

Preferably the valve seat is a second valve disk and has an opposingsurface on the other side of the disk from the contact surface.

Preferably the two adjacent inlet apertures of the second valve diskhave a greater area in the plane of the contact surface of the secondvalve disk than in the plane of the opposing surface of the second valvedisc.

Preferably the substantially sector shaped outlet aperture of the valvemember at the plane of the valve member contact surface has an angle ofabout 120 degrees at its apex.

Preferably the two adjacent substantially sector shaped inlet aperturesof the valve seat at the plane of the valve seat contact surface, eachhave an approximately 90 degree apex.

Preferably the outlet aperture in the valve member is in the shape of aremoved sector.

Preferably the valve seat contact surface has a recessed region. In asecond aspect, the invention may broadly be said to consist in a servoactuated fluid mixing valve, comprising: a valve body having at leasttwo fluid inlet ports and at least one fluid outlet port; a servoactuator attached to said valve, a valve seat having a valve seatcontact surface and an outlet valve member having an outlet membercontact surface, the valve member being capable of being rotated about afirst axis by said servo actuator, said valve seat having two adjacentinlet apertures there through separated by a dividing piece, and saidvalve seat having a closed area opposite the inlet apertures, a firstsaid inlet aperture communicating with a first of said two inlet ports,and a second said inlet aperture communicating with a second of said twoinlet ports, a barrier on the inlet side of the valve seat separatingthe fluid flow from said at least two inlet ports so that the twosupplies of fluids do not mix until after they have passed through thetwo inlet apertures in the valve seat; said valve member having anoutlet aperture there through and a sealing area, said outlet aperturecommunicating with said at least one outlet port, the valve membercontact surface and the valve seat contact surface being arranged insubstantially planar sealing contact with one another, and the valvemember is capable of rotation relative to the valve seat, wherein theoutlet aperture of the valve member is substantially sector shaped atthe plane of the valve member contact surface, with its sector apex ator close to the point of intersection of the first axis with the valvemember and with its arc at or close to the outside of the valve member,and the two adjacent inlet apertures of the valve seat are eachsubstantially sector shaped at the plane of the valve seat contactsurface with each having its sector apex close to the point ofintersection of the first axis with the valve seat, and the sealing areaof the valve member is greater than or equal to the combined area of thetwo adjacent inlet substantially sector shaped apertures so that thesealing area of the valve member can cover and close the two adjacentinlet substantially sector shaped apertures, whereby the valve membercan be rotated about the first axis between a shut off position whereboth of the inlet apertures are closed by the valve member, a firstinlet opened position where the first inlet aperture and the outletaperture are aligned to allow fluid to flow from the first inlet portthrough the first inlet aperture via the outlet aperture to the outletport, whilst at the same time the second inlet aperture is closed by thevalve member, a second inlet opened position where the second inletaperture and the outlet aperture are aligned to allow fluid to flow fromthe second inlet port through the second inlet aperture via the outletaperture to the outlet port, whilst at the same time the first inletaperture is closed by the valve member, and a mixing position whereinthe outlet aperture overlaps with both of the inlet apertures to allowfluids to flow from said two inlet ports through the two inlet aperturesand through the outlet aperture, and mix downstream of the outletaperture so that the fluids can exit the outlet port.

Preferably the servo actuator includes a stepping motor.

Preferably the servo actuated fluid mixing valve further includes acontroller means.

Preferably the servo actuated fluid mixing valve further includes asensing means which is positioned and adapted to sense at least oneparameter relating to any fluid which passes through the at least onefluid outlet port, allowing feed-back control of the valve.

Preferably the servo actuated fluid mixing valve further includes acontroller means.

Preferably the servo actuator includes a stepping motor.

Preferably the servo actuated fluid mixing valve further includes a userinterface means.

Preferably the valve member is a first valve disk.

Preferably the valve seat is a second valve disk and has an opposingsurface on the other side of the disk from the contact surface.

Preferably the two adjacent inlet apertures of the second valve diskhave a greater area in the plane of the contact surface of the secondvalve disk than in the plane of the opposing surface of the second valvedisc.

Preferably the substantially sector shaped outlet aperture of the valvemember at the plane of the valve member contact surface has an angle ofabout 120 degrees at its apex.

Preferably the two adjacent substantially sector shaped inlet aperturesof the valve seat at the plane of the valve seat contact surface, eachhave an approximately 90 degree apex.

Preferably the outlet aperture in the valve member is in the shape of aremoved sector.

Preferably the valve seat contact surface has a recessed region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 & 1A: Respectively show top and bottom views of a part of avalve in accordance with an embodiment of the present invention.

FIG. 2: Shows a side view of the part shown in FIGS. 1 and 1A.

FIG. 3: Shows a plan view of another part of a valve according to thesame embodiment of the present invention.

FIG. 4: Shows a side view of the parts shown in FIG. 3.

FIG. 5: Shows a part of a valve corresponding to the parts shown inFIGS. 1 and 2 according to an alternative embodiment of the presentinvention.

FIG. 6: Shows a side plan view of a part shown in FIG. 5.

FIG. 7: Shows a gasket which corresponds to the part of the valve shownin FIGS. 1, 1A and 2.

FIG. 8: Shows a side view of the gasket shown in FIG. 7.

FIGS. 9 & 9A: Shows part of a gasket used to seal either of the partsshown in FIGS. 1 and 2 or 5 and 6.

FIGS. 10 & 10A: Shows two reinforcement members for the gasket shown inFIG. 9;

FIG. 11: Shows a valve assembly incorporating the parts shown in FIGS. 1to 10 of either embodiment.

FIG. 12: Shows a servo valve system according to an embodiment of thepresent invention and incorporating the valve assembly shown in FIG. 11.

FIG. 13: Shows a servo valve system according to an alternativeembodiment and incorporating the valve assembly shown in FIG. 11.

FIG. 14: Shows a servo valve system according to an alternativeembodiment of the present invention.

FIG. 15: Shows the layout of a user interface for a servo valve systemaccording to an alternative embodiment of the present invention.

FIG. 16: Schematically shows a mixing system according to an embodimentof the present invention.

FIGS. 17-20: Show a combination mixing and diverting servo valve systemaccording to a further embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1, 1A and 2 show an inlet valve member 1 which, in use, is alignedperpendicular to a flow of fluid through the valve. The inlet valvemember 1 includes two apertures 2 and 3 through which fluid passes whenthe valve is open. Typically, these apertures 2 and 3 have a crosssection that is sectorial or elliptical at one face of the valve member1 and circular at the other, although any suitable cross sectional shapemay be substituted. The apertures 2 and 3 are, typically, formedcircular at the face of the inlet valve member 1 which is in contactwith the fluid supply and the size of the circles are minimised, withinconstraints of required flow. In use, only the apertures 2 and 3 and aminimal area around the apertures are in contact with the fluid supplyto minimise pressure being exerted on the inlet valve member 1 whichwould increase friction between the inlet valve member 1 and an outletvalve member 10, described with reference to FIG. 3 below. Also,typically, the apertures 2 and 3 are positioned inward from theperiphery of the valve member 1 to provide an area of the valve member 1peripheral to the apertures against which another member may abut toseal the apertures 2 and 3 when required. However, suitable alternativesealing arrangements will be apparent to those skilled in the art.

The apertures 2 and 3 may have different relative sizes to account forrelative differences in supply pressures or viscosity, for example.

The inlet valve member may typically have a recessed region 5 formed inthe contact side 6 of the inlet valve member 1 and grooves 6 a to reducefriction with any flat surface in contact with the contact side 6 of theinlet valve member 1. Such friction reduction measures reduce theactuation torque required by the valve. The edges of the inlet valve 1may, typically, be bevelled to prevent chipping of the edges of thevalve member 1.

The inlet valve member includes alignment tabs 7 with which it may beheld in a given orientation.

FIGS. 3 and 4 show the outlet valve member 10. The valve member 10 has acontact surface 11 which may be flat so that the outlet valve member 10may be sealingly abutted against the contact side 6 of the inlet valvemember 1 in use to seal the apertures 2 and 3 when required.

The outlet valve member 10 is of the form of a disk with a removedsector 12. It will be apparent to those skilled in the art thatalternative shapes to the removed sector 12 may suitably be substitutedand that the shape may be optimised for particular applications. In use,the outlet valve member 10 is abutted and aligned with the inlet valvemember 1 and depending on its orientation with respect thereto, variablyimpedes the flow of fluid emerging from the apertures 2 and 3. The flowwill be completely impeded and the apertures 2 and 3 sealed when theremoved sector 12 of the outlet valve member 10 does not overlap eitherof the apertures 2 or 3. The flow of fluid through each of the apertures2 and 3 can be varied from nil flow to an unimpeded flow or a controlledratio of flow through each conduit. Thus, the outlet valve member 10 andinput valve member 1 may be combined to form a mixing valve.Alternatively, they may be reversed and combined to form a divertingvalve. Alternatively, an inlet valve member 1 having only one aperturemay be used to control the flow of a single fluid, or both apertures ofthe inlet valve member 1 may communicate with a single fluid supply forthe same purpose.

Typically, each aperture 2 and 3 communicates with a separate fluidsupply conduit, not shown, and the output of the valve communicates witha single output conduit so that the valve allows the variable mixing ofthe fluids from the two supply conduits.

The outlet valve member 10 includes actuation recesses 13 by which itmay be rotated.

The size of the removed sector 12 in conjunction with the size of theapertures 2 and 3 determines the maximum flow rate for given fluids atgiven temperatures and pressures.

FIGS. 5 and 6 show an alternative inlet valve member 1 which includesapertures 2 and 3 having a sectorial cross-section of greater area thanthose of the inlet valve member shown in FIGS. 1 and 2. It will be clearto those skilled in the art that other conduit sizes and shapes may besubstituted as applicable to given applications of the valve.

FIGS. 7 and 8 show a seal, or gasket, 85 used in conjunction with theinlet valve member 1 shown in FIGS. 1, 1A and 2. The use of the gasket85 is explained with reference to FIG. 11 below.

FIGS. 9 to 10 a show alternative gasket elements 28 and 29, which arecombined to form a gasket for sealing inlet valve members 1 shown inFIGS. 5 and 6. The gasket elements 28 are, typically, formed fromsilicon, rubber or other suitable deformable material, and gasketelements 29 are, typically, formed from plastic and serve the purpose ofreinforcing the gasket element 28.

FIG. 11 shows a valve assembly 19, including the inlet valve member 1and outlet valve member 10 of either of the embodiments described above.These valve members are fitted inside a valve chassis 20. The removedsector 12 of the outlet valve member 10 and the valve chassis 20 definean outlet aperture. The valve chassis 20 is open at one end to form avalve chassis inlet 21. A valve chassis outlet 22 is formed in the sideof the valve chassis 20. In use, the valve assembly 19 is fitted into avalve housing 35 as described with reference to FIG. 12 below. An O-ring23 is used to seal the valve assembly 19 in the valve housing 35.

The valve assembly 19 includes a spindle assembly 24, which engages theactuation recesses 13 of the outlet valve member 10. The outlet valvemember 10 can be rotated by rotation of the spindle assembly 24, whichincludes a spline 25 formed at one end to facilitate turning of thespindle assembly 24.

The inlet valve member 1 is, typically, held in fixed alignment by thealignment tabs 7 which engage corresponding alignment recesses, notshown, in the valve assembly chassis 20. The spindle assembly 24 issealed within the valve assembly chassis 20 by use of O-rings andwashers.

The gasket 85 or that formed from gasket members 28 and 29 is fittedinto the inlet end of the valve assembly chassis 20.

The working of the valve assembly is illustrated below with reference tohot and cold water, each being supplied by one separate conduit 2 or 3,as would be the case with an application such as a shower temperaturecontrol mixing valve.

The outlet valve member 10 is initially orientated so as to cover orseal both of the apertures 2 and 3 of the inlet valve member 1. Thespindle 24 is then turned in an opening direction to initially uncoverpart of the aperture 2, for example, which is supplied with cold water.Continued turning in the same direction increasingly uncovers theaperture 2. Eventually, continued turning will uncover the otheraperture 3 to which hot water is supplied and partially cover theaperture 2. The ratio of hot and cold water may be adjusted by turningthe spindle 24 in the same direction or in the opposite direction.Having sectorial inlet and outlet apertures, provides that the valve hasa substantially linear flow response with respect to rotational angle.

At a mid point, equal portions of each aperture are uncovered anddepending on the chosen shape and size of the apertures 2 and 3 andsector 12, this may correspond to partial covering of both apertures 2and 3.

Further turning may result in only the aperture 3 being uncovered andonly hot water being supplied to the valve chassis outlet 22.

FIG. 12 shows a side view of a servo valve system 30, which includes thevalve assembly 19 described above.

The servo valve system 30 also includes an inlet manifold 31 having twoinlets 32, one of which is shown in FIG. 12 and the other of which ispositioned directly behind a dividing wall 33, as shown in FIG. 12. Adividing piece 8 of the inlet valve member 1, which divides the twoapertures 2 and 3 is aligned with the dividing wall 33. The gasket 28 or85 is aligned accordingly. It may be preferable that the gasket 28 orthe inlet manifold 31 are shaped like gasket 85 so that only theapertures of the inlet valve member 1 are in contact with the fluidsupply as otherwise force exerted on the inlet valve member 1 causesincreased friction between the inlet valve member 1 and the outlet valvemember 10 which requires an increase actuation torque.

The servo valve system 30 includes an outlet pipe 34 connected at theoutlet 22 of the valve assembly 19. Typically, but not necessarily, theoutlet pipe 34 is integrally formed from the servo valve system housing35.

The valve assembly 19 is secured in the housing 35 with an annular cap36 and sealed at the top with the O-ring 23.

The inlet manifold 31 is sealed to the housing 35 with an O-ring 37.

The servo valve system 30 includes a stepper motor 38, or some otherautomated driving device such as a DC motor, AC motor or hydraulicmotor, to actuate the spindle 24 at the spline 25 through a gear box 39.It will be apparent to those skilled in the art that a wide variety ofstepper motors may be used with suitable gear boxes or that a spline 25of suitable diameter may eliminate the need for a gearbox 39 in somecases. By the use of the friction reducing measures described above, aminimally sized stepper motor may be used reducing the size and requiredresources of the device.

The servo valve system 30 may include one or more sensors, not shown, inthe input manifold 31, but more particularly in the outlet pipe 34 toprovide feedback for the control of the servo valve system 30.

The sensors may include temperature sensors. For example, a thermistormay be inserted through the side of the outlet pipe 34 to monitortemperature of the water, say, in the outlet pipe 34 and to allowsuitable adjustment by the stepper motor 38 to control temperature ofwater in the outlet pipe 34 in the case where different temperaturefluid supplies are connected to the inlet manifold 31.

FIG. 13 shows a servo valve system 40 according to an alternativeembodiment of the present invention. The servo valve system 40 differsfrom the servo valve system 30 described above, only by the inclusion ofan extra output pipe 41 which may be opened or closed by way of asolenoid valve 42. In one application, the outlet pipe 34 supplies ahand held shower head and the output pipe 41 supplies a midriff heightshower jet. The solenoid valve 42 opens and closes water supplied to thehand held shower head as desired.

FIG. 14 shows a side view of a servo valve system 50 according toanother aspect of the present invention.

The servo valve system 50 includes two individual valves such as 51shown each being supplied by individual inlet pipes, such as 52 shown.

The valves consist of conventional apertured ceramic disks mounted in achassis with two outlets on opposite sides of the chassis.

The ceramic disks each include two opposing apertures, typicallysectorial in shape. To open the valve, one of the disks is rotated byway of the spindle so that the apertures of both disks overlap.

The outlets of both valve assemblies feed a single intermediary conduit55. Each valve is actuated at the respective spline 54 of the respectivespindle 53 by a respective gearbox 61 and a respective stepper motor 62.

As each valve controls the inflow of fluid from a separate inlet, theratio of fluids from each inlet as well as the total flow from bothinlets can be adjusted.

Typically, the stepper motors are controlled such that once a desiredflow in the intermediary pipe 55 is achieved, an adjustment to one valveis accompanied by a negative adjustment of the other, so that the mix offluid in the intermediary pipe 55, or temperature, can be adjustedwhilst the pressure is maintained. This may be modified to take accountof relative differences in supply pressures that occur where non mainspressure water supply systems are used.

The servo valve system 50 also includes an outlet manifold 56 which,typically, has two final outlets such as 57 and 58, each including asolenoid valve such as 59 and 60.

One embodiment incorporating this aspect of the present invention isintended for use with a shower unit, which has two fixed shower heads,one at head height and one at midriff height, for example. Thisembodiment is supplied with hot and cold water at separate inlets andincludes a thermistor inserted into the intermediary chamber 55 toprovide feedback on temperature for appropriate control of the twovalves such as 51. Thus, a drop in one or the other of the watersupplies will be compensated in terms of temperature without the needfor a pressure feedback, although this may be included if desired.

This embodiment is able to compensate for changes in supplied pressureof either or both the hot and cold water so that a constant desiredtemperature and constant desired pressure is provided at the showerheads. It may also compensate for changes in pressure at one or two ofthe final outlets such as 57 and 58 in the event that one or two of theother final outlets are opened or closed.

One preferred embodiment of the present invention is directed for use inbathroom showers where it provides relatively constant temperature waterfor shower heads. It will be clear to those skilled in the art that thebathroom shower is merely an example application and that many analogousapplications of this embodiment exist and that the mixing of water ofdifferent temperatures may be analogous to the mixing of fluids havingother physical or chemical properties. A few examples are ph, viscosity,dielectric constant, or content of a given chemical or biological agent.

The bathroom shower mixing system is supplied with two fluids, hot andcold at given pressures. These are mixed by a servo valve systemaccording to any of the embodiments described above and information onthe temperature of the mixed fluid is fed back to the controller of theservo valve system. In the case of the servo valve system 50 being used,information on pressure can be estimated by the known position of thestepper motors and so pressure may be maintained.

The temperature sensors are typically negative temperature coefficientsensors. Some inherent nonlinearity of the temperature signals may bepartially compensated with the sensor electronics before quantisation bythe microprocessor. The microprocessor contains software that comparesthe measured temperature with a predefined reference temperature. Fromthis, and with an appropriate control algorithm, again, themicroprocessor determines the required position of the stepper motors,and therefore, the valve members 1 and 10. It will be understood bythose skilled in the art that calibration of the system will benecessary and suitable calibration will be apparent.

To maintain excellent speed and torque characteristics whilstmaintaining good angular resolution and minimal microprocessor resource,the stepper motors are, preferably, operated at two speeds using twodifferent stepping modes.

The motor is “full-stepped” for large displacements. This optimises thespeed and torque response.

The motor is “half-stepped” for temperature adjustments. This optimisesthe resolution of movements.

The motors are half-stepped at the start of an acceleration from restand later full-stepped. Similarly, the motors are half-stepped at theend of a deceleration to rest and after full-stepping. These measuresreduce mechanical shock and overcome inertia of the motor, gearbox andvalve assembly.

The mixer system also includes protection against the valve being leftopen in the event of loss of electrical power. Two methods are employedin the preferred embodiment. One method includes the use of batterieswhich store enough energy to close the valve assembly when power loss isdetected. The other method includes the use of solenoids that requirepower to remain open and, thus the flow is shut off when the powerfails.

FIG. 15 shows a user interface 60 for a preferred embodiment of thebathroom shower mixing system that includes the servo valve system 50.

The user interface 60 includes an LCD display 61 for displaying thedesired and/or actual water temperature and ± button system 62 foradjusting the desired water temperature.

A set of three buttons 63 are also included to switch on/off a showerrose, perhaps, fixed at head height, shower jets, perhaps, fixed atmidriff height and a hand held shower rose. The set of buttons 64 areincluded for user programmable preset functions for, perhaps,temperature and combinations of outlets and lights. Button 65 controlsan economy mode which may reduce water flow by 25% or 50%. Button 66 maybe used to set the shower duration with increments of 30 seconds. Button67 switches on/off a “Swedish” cycle which fluctuates the showertemperature between hot and cold.

FIG. 16 schematically shows the operation of a servo valve system inaccordance with an embodiment of the present invention.

Information on a desired value of a given parameter, such as temperatureof fluid leaving the valve system, is received from the user interface71. This information is fed to the system controller 72. The systemcontroller 72 receives information from a sensor at the output of thevalve system and includes an analogue to digital converter 73 toquantify the parameter value sensed by the sensor. The position of thestepper motor and gearbox 75 is then calculated by the microcontroller74 and then converted to a stepper sequencer 81. The stepper motor andgearbox 75 are then driven by the stepper driver 76 to the requiredposition. By actuation of the stepper motor and gearbox 75, the mixingassembly 77 is placed in a suitable position to mix the inlet fluids 78and 79 to form an outlet fluid 80. Information on the given parameter isthen fed back to the microcontroller 74 and the process repeated by wayof adjustment.

It will be apparent to those skilled in the art that an alternativeembodiment to those described above may include a valve assembly 19 usedin reverse where water is fed into the outlet 22 from a single supplyand from there diverted into either of the apertures 2 or 3 of the, now,outlet member 1.

FIGS. 17 to 20 show a further embodiment of the present invention. Thisis a combined valve provided to control temperature, pressure and alsodirect flow between alternative outlets. The fluid control valve 90shown in FIGS. 17 to 20 may control the flow of hot and cold waterindependently to alternative outlets. The valve 90 may comprise a mainbody portion 91 having hot and cold water inlets 92 and 93 respectively.Valve members 94 and 95 may be provided in cooperating pairs acting toindependently control the flow of hot and cold water respectively. Thesecooperating pairs may be prepared as pairs of valve members inaccordance with valve members 1 and 10, although it will be preferablethat the inlet valve member/and outlet is valve member 10 are swapped sothat the “outlet” valve member 10 now communicates directly with thefluid supply.

It can be seen that the outlet from the valve members 94 and 95 allowsflow into either one of two mixing chambers 96 and 97, each connectedwith separate outlets 98 and 99. Further, control of the valve members94 and 95 and the relative rotation of one with the other is provided bystepper motors 100 and 101. These stepper motors may be controlled by acontroller which may receive feedback information on temperature, orsome other fluid parameter, at the outlet.

It can be seen that a valve of this type may be mounted on aninstallation to divert flow between a shower head or a bath spout, forexample. The temperature at the outlet may be controlled throughindependent control over the flow of hot and cold fluid into the mixingchambers through the valve members 94 and 95 by control of the steppermotors 100 and 101. Furthermore, if the valve members 94 and 95 areindependently controlled, the flow rate from the valve may be controlledby controlling the degree to which each of these valve members areopened.

This assembly allows servo control over the direction, flow rate andfluid temperature in a single installation.

In all the valve assemblies filters may be incorporated either withinthe valve or upstream to inhibit the entry of particulate matter intothe valve which may affect the valve control.

Although the above described embodiments have been described inreference to the mixing of two fluids, it will be apparent to thoseskilled in the art that the valve or valve systems may find usefulapplication in controlling the flow of a single fluid and that this ismerely a simpler application than controlling the flow of two fluids.One possible example of a single fluid application is in the control ofwater supplied to a urinal. For single fluid applications, the valvemember 1 described above may be used with both apertures 2 and 3communicating with a single fluid supply. An alternative embodimentincludes an inlet valve member, not shown, similar to the inlet member1, but consisting of only one inlet aperture.

The present invention provides an effective servo valve system which canactively compensate for fluctuations in relative supply of two or morefluids. This may, for example, be desirable for shower mixers where thehot and cold water supply pressures may fluctuate due to use in anotherpart of a building, for example.

Another embodiment of the present invention provides a servo valvesystem, which may actively adjust, for flow or relative and absolutechanges in the supply pressure of two or more supplied fluids. This may,for example, be useful for shower mixing units where constant flow aswell as constant temperature is desired. This may be particularly usefulwhere the shower mixer has multiple outlets and adjustment of supplypressure is necessary to compensate for sudden changes in outflowthrough the outlets.

The present invention provides servo control valve systems whichincorporate stepper motors which are, by their nature, suited to servocontrol applications and eliminate the need for systems for monitoringthe position of the valves or motors.

Where in the foregoing description, reference has been made to specificcomponents or integers of the invention having known equivalents thensuch equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and withreference to possible embodiments thereof, it is to be understood thatmodifications or improvements may be made thereto without departing fromthe scope or spirit of the invention, as defined in the appended claims.

1. A fluid mixing valve for servo control of fluid flows, comprising: avalve body having at least two fluid inlet ports and at least one fluidoutlet port; a valve seat having a fixed valve seat contact surfaceadjacent a movable outlet valve member having an outlet member contactsurface, the outlet valve member being rotatable about a first axis;said valve seat having two adjacent inlet apertures there throughseparated by a dividing piece, and said valve seat having a closed areaopposite the inlet apertures, a first said inlet aperture communicatingwith a first of said two inlet ports, and a second said inlet aperturecommunicating with a second of said two inlet ports, a barrier on theinlet side of the valve seat separating the fluid flow from said atleast two inlet ports so that the two supplies of fluids do not mixuntil after they have passed through the two inlet apertures in thevalve seat; said outlet valve member having an outlet aperture therethrough and a sealing area, said outlet aperture communicating with saidat least one outlet port, the outlet valve member contact surface andthe valve seat contact surface being arranged in substantially planarsealing contact with one another, the outlet valve member capable ofrotation relative to the valve seat, wherein, the outlet aperture of theoutlet valve member is substantially sector shaped at the plane of theoutlet member contact surface, with a sector apex at or close to thepoint of intersection of the first axis with the outlet valve member andwith an arc at or close to the outside of the outlet valve member, andthe two adjacent inlet apertures of the valve seat are eachsubstantially sector shaped at the plane of the valve seat contactsurface with each having a sector apex close to the point ofintersection of the first axis with the valve seat, the sealing area ofthe valve member is greater than or equal to the combined area of thetwo adjacent inlet substantially sector shaped apertures so that thesealing area of the outlet valve member can cover and close the twoadjacent inlet substantially sector shaped apertures, and the outletvalve member can be rotated about the first axis between a) a shut offposition where both of the inlet apertures are closed by the outletvalve member, b) a first inlet opened position where the first inletaperture and the outlet aperture are aligned to allow fluid to flow fromthe first inlet port through the first inlet aperture via the outletaperture to the outlet port, whilst at the same time the second inletaperture is closed by the outlet valve member, c) a second inlet openedposition where the second inlet aperture and the outlet aperture arealigned to allow fluid to flow from the second inlet port through thesecond inlet aperture via the outlet aperture to the outlet port, whilstat the same time the first inlet aperture is closed by the outlet valvemember, and d) a mixing position wherein the outlet aperture overlapswith both of the inlet apertures to allow fluids to flow from said twoinlet ports through the two inlet apertures and through the outletaperture, and mix downstream of the outlet aperture so that the fluidscan exit the outlet port.
 2. A fluid mixing valve as claimed in claim 1,wherein the outlet valve member is a first valve disk.
 3. A fluid mixingvalve as claimed in claim 1, wherein the valve seat is a second valvedisk and has an opposing surface on the other side of the disk from thecontact surface.
 4. A fluid mixing valve as claimed in claim 3, whereinthe two adjacent inlet apertures of the second valve disk have a greaterarea in the plane of the contact surface of the second valve disk thanin the plane of the opposing surface of the second valve disc.
 5. Afluid mixing valve as claimed in claim 1, wherein the substantiallysector shaped outlet aperture of the valve member at the plane of theoutlet valve member contact surface has an angle of about 120 degrees atits apex.
 6. A fluid mixing valve as claimed in claim 1, wherein the twoadjacent substantially sector shaped inlet apertures of the valve seatat the plane of the valve seat contact surface, each have anapproximately 90 degree apex.
 7. A fluid mixing valve as claimed inclaim 1, wherein the outlet aperture in the outlet valve member is inthe shape of a removed sector.
 8. A fluid mixing valve as claimed inclaim 1, wherein the valve seat contact surface has a recessed region.9. A servo actuated fluid mixing valve, comprising: a valve body havingat least two fluid inlet ports and at least one fluid outlet port; aservo actuator attached to said valve, a valve seat having a valve seatcontact surface adjacent an outlet valve member having an outlet membercontact surface, the valve member being capable of being rotated about afirst axis by said servo actuator, said valve seat having two adjacentinlet apertures there through separated by a dividing piece, and saidvalve seat having a closed area opposite the inlet apertures, a firstsaid inlet aperture communicating with a first of said two inlet ports,and a second said inlet aperture communicating with a second of said twoinlet ports, a barrier on the inlet side of the valve seat separatingthe fluid flow from said at least two inlet ports so that the twosupplies of fluids do not mix until after they have passed through thetwo inlet apertures in the valve seat; said valve member having anoutlet aperture there through and a sealing area, said outlet aperturecommunicating with said at least one outlet port, the valve membercontact surface and the valve seat contact surface being arranged insubstantially planar sealing contact with one another, and the valvemember is capable of rotation relative to the valve seat, wherein, theoutlet aperture of the valve member is substantially sector shaped atthe plane of the valve member contact surface, with its sector apex ator close to the point of intersection of the first axis with the valvemember and with its arc at or close to the outside of the valve member,the two adjacent inlet apertures of the valve seat are eachsubstantially sector shaped at the plane of the valve seat contactsurface with each having its sector apex close to the point ofintersection of the first axis with the valve seat, the sealing area ofthe valve member is greater than or equal to the combined area of thetwo adjacent inlet substantially sector shaped apertures so that thesealing area of the valve member can cover and close the two adjacentinlet substantially sector shaped apertures, and the valve member can berotated about the first axis between a) a shut off position where bothof the inlet apertures are closed by the valve member, b) a first inletopened position where the first inlet aperture and the outlet apertureare aligned to allow fluid to flow from the first inlet port through thefirst inlet aperture via the outlet aperture to the outlet port, whilstat the same time the second inlet aperture is closed by the valvemember, c) a second inlet opened position where the second inletaperture and the outlet aperture are aligned to allow fluid to flow fromthe second inlet port through the second inlet aperture via the outletaperture to the outlet port, whilst at the same time the first inletaperture is closed by the valve member, and d) a mixing position whereinthe outlet aperture overlaps with both of the inlet apertures to allowfluids to flow from said two inlet ports through the two inlet aperturesand through the outlet aperture, and mix downstream of the outletaperture so that the fluids can exit the outlet port.
 10. A servoactuated fluid mixing valve as claimed in claim 9, wherein the servoactuator includes a stepping motor.
 11. A servo actuated fluid mixingvalve as claimed in claim 9, further including a controller means.
 12. Aservo actuated fluid mixing valve as claimed in claim 9, furtherincluding a sensing means which is positioned and adapted to sense atleast one parameter relating to any fluid which passes through the atleast one fluid outlet port, allowing feed-back control of the valve.13. A servo actuated fluid mixing valve as claimed in claim 12, furtherincluding a controller means.
 14. A servo actuated fluid mixing valve asclaimed in claim 12, wherein the servo actuator includes a steppingmotor.
 15. A servo actuated fluid mixing valve as claimed in claim 13,wherein the servo actuator includes a stepping motor.
 16. A servoactuated fluid mixing valve as claimed in claim 9, further including auser interface means.
 17. A servo actuated fluid mixing valve as claimedin claim 12, further including a user interface means.
 18. A servoactuated fluid mixing valve as claimed in claim 15, further including auser interface means.
 19. A servo actuated fluid mixing valve as claimedin claim 9, wherein the valve member is a first valve disk.
 20. A servoactuated fluid mixing valve as claimed in claim 9, wherein the valveseat is a second valve disk and has an opposing surface on the otherside of the disk from the contact surface.
 21. A servo actuated fluidmixing valve as claimed in claim 20, wherein the two adjacent inletapertures of the second valve disk have a greater area in the plane ofthe contact surface of the second valve disk than in the plane of theopposing surface of the second valve disc.
 22. A servo actuated fluidmixing valve as claimed in claim 9, wherein the substantially sectorshaped outlet aperture of the valve member at the plane of the valvemember contact surface has an angle of about 120 degrees at its apex.23. A servo actuated fluid mixing valve as claimed in claim 9, whereinthe two adjacent substantially sector shaped inlet apertures of thevalve seat at the plane of the valve seat contact surface, each have anapproximately 90 degree apex.
 24. A servo actuated fluid mixing valve asclaimed in claim 9, wherein the outlet aperture in the valve member isin the shape of a removed sector.
 25. A servo actuated fluid mixingvalve as claimed in claim 9, wherein the valve seat contact surface hasa recessed region.
 26. A servo-controlled fluid mixing valve,comprising: a valve body having at least two fluid inlet ports and atleast one fluid outlet port; a valve cavity housing a non-movable fixedinlet side valve disk adjacently contacting a single movable outlet sidevalve disk, the inlet side valve disk and the outlet side valve diskbeing arranged in substantially planar sealing contact with one another,the outlet side valve disk rotatable relative to the inlet side valvedisk, the movable valve disk being rotatable about a first axis ofmotion to provide fluid mixing control and flow on/off control offluids, via flow through the movable disk from the inlet ports to theoutlet port, the movable outlet side valve disk being free of linearmotion along the first axis; a single stepper motor actuator operativelyconnected to the movable outlet side valve disk to rotate the movableoutlet side valve disk about the first axis and provide the fluid mixingcontrol and the flow on/off control through only rotatinglyrepositioning the movable outlet side valve disk by the stepper motoractuator; said inlet side valve disk having two adjacent inlet aperturesseparated by a dividing piece, said inlet side valve disk being a closedarea other than at the inlet apertures, a first of said inlet aperturescommunicating with a first of said two inlet ports, and a second of saidinlet apertures communicating with a second of said two inlet ports, abarrier on the inlet side of the valve seat separating the fluid flowfrom said at least two inlet ports so that the two supplies of fluids donot mix until after they have passed through the two inlet apertures;said movable outlet side valve disk having an outlet aperture therethrough and a sealing area, said outlet aperture communicating with saidat least one outlet port, wherein, the outlet aperture of the outletside valve disk substantially sector shaped at the plane of the outletside valve disk with a sector apex at or adjacent a point ofintersection of the first axis with the outlet side valve disk and withan arc at or adjacent an outside of the outlet side valve disk, and thetwo adjacent inlet apertures of the inlet side valve disk are eachsubstantially sector shaped at the plane of the inlet side valve diskwith each aperture having a corresponding sector apex adjacent to thepoint of intersection of the first axis with the inlet side valve disk,the sealing area of the outlet side valve disk is at least equal to acombined area of the two adjacent inlet substantially sector shapedapertures so that the sealing area of the outlet side valve disk cancover and close the two adjacent inlet substantially sector shapedapertures, and the outlet side valve disk can be rotated by the actuatorabout the first axis between a) a shut off position where both of theinlet apertures are closed by the outlet side valve disk, b) a firstinlet opened position where the first inlet aperture and the outletaperture are aligned to allow fluid to flow from the first inlet portthrough the first inlet aperture via the outlet aperture to the outletport, whilst at the same time the second inlet aperture is closed by theoutlet side valve disk, c) a second inlet opened position where thesecond inlet aperture and the outlet aperture are aligned to allow fluidto flow from the second inlet port through the second inlet aperture viathe outlet aperture, to the outlet port, whilst at the same the firstinlet aperture is closed by the outlet side valve disk, and d) a mixingposition wherein the outlet aperture overlaps with both of the inletapertures to allow fluids to flow from said two inlet ports through thetwo inlet apertures and through the outlet aperture, and mix downstreamof the outlet aperture so that the fluids can exit the outlet port.